Answer: 2sin -1 (n sin(A/2)) - A.
- A A(n-1), the thin-prism small-angle approximation
- B 2sin<sup>-1</sup>(n sin(A/2)) - A
- C n-1, omitting the apex angle dependence entirely
- D (n-1)/A, inverting the role of the apex angle
Correct answer: B. 2sin<sup>-1</sup>(n sin(A/2)) - A
Explanation: n = sin((A+D<sub>min</sub>)/2) / sin(A/2). So D<sub>min</sub> = 2sin<sup>-1</sup>(n sin(A/2)) - A.
Concave mirror ray construction: a ray parallel to the axis reflects through F, and a ray through F reflects parallel, locating the inverted real image. Image: Maxmath12, CC0, via Wikimedia Commons.
Concept context
Reflection, refraction, lenses, mirrors, total internal reflection.